1. Field of the Invention
This invention relates to an improvement of a locking and unlocking device applicable to the locking and unlocking of doors of automobiles, for example.
2. Description of the Prior Art
In conventional automobile door locking devices it has been common practice to adopt the structure comprising two actuators or an actuator constructed to effect pushing and pulling operations by having two exciting coils therein, for example, thereby to produce a force in two directions for locking or unlocking which is applicable to a locking and unlocking mechanism according to an unlocked or locked state of the door locking device, respectively. With such structure, the changing of the direction of application of the force has been achieved by energizing either one of the two actuators or of the two exciting coils according to the locked or unlocked state of the door locking device. However, the above-mentioned conventional structure requires the use of two actuators or two exciting coils, which gives rise to a grave drawback to increase cost and weight of a product using such a device. Such a drawback is a contradiction to a recent trend in the automotive industry to lower the weight of automobiles with the object of reducing production cost and improving fuel consumption.